Work these simultaneous equations out on paper and write down your answers.

[tex]\[
\begin{array}{ll}
3x + 4y = 13 & x = 3 \\
6x - y = 17 & y = 1 \\
3a + b = 13 & a = \square \\
6a - 7b = -10 & b = \square \\
6p - 7q = 23 & p = \square \\
18p - q = 89 & q = \square \\
5m - 2n = 20 & m = \square \\
10m + 7n = 95 & n = \square
\end{array}
\][/tex]



Answer :

Sure! Let's work through the simultaneous equations step-by-step.

### Equations for [tex]\(a\)[/tex] and [tex]\(b\)[/tex]:

Given equations:
1. [tex]\(3a + b = 13\)[/tex]
2. [tex]\(6a - 7b = -10\)[/tex]

We need to solve these equations simultaneously. Here's how:

Step 1: Solve the first equation for [tex]\(b\)[/tex]:
[tex]\[ b = 13 - 3a \][/tex]

Step 2: Substitute this expression for [tex]\(b\)[/tex] into the second equation:
[tex]\[ 6a - 7(13 - 3a) = -10 \][/tex]

Step 3: Simplify and solve for [tex]\(a\)[/tex]:
[tex]\[ 6a - 91 + 21a = -10 \][/tex]
[tex]\[ 27a - 91 = -10 \][/tex]
[tex]\[ 27a = 81 \][/tex]
[tex]\[ a = 3 \][/tex]

Step 4: Substitute [tex]\(a = 3\)[/tex] back into the expression for [tex]\(b\)[/tex]:
[tex]\[ b = 13 - 3 \cdot 3 \][/tex]
[tex]\[ b = 13 - 9 \][/tex]
[tex]\[ b = 4 \][/tex]

So, the solutions for [tex]\(a\)[/tex] and [tex]\(b\)[/tex] are:
[tex]\[ a = 3, \quad b = 4 \][/tex]

### Equations for [tex]\(p\)[/tex] and [tex]\(q\)[/tex]:

Given equations:
1. [tex]\(6p - 7q = 23\)[/tex]
2. [tex]\(18p - q = 89\)[/tex]

We need to solve these equations simultaneously. Here's how:

Step 1: Solve the second equation for [tex]\(q\)[/tex]:
[tex]\[ q = 18p - 89 \][/tex]

Step 2: Substitute this expression for [tex]\(q\)[/tex] into the first equation:
[tex]\[ 6p - 7(18p - 89) = 23 \][/tex]

Step 3: Simplify and solve for [tex]\(p\)[/tex]:
[tex]\[ 6p - 126p + 623 = 23 \][/tex]
[tex]\[ -120p + 623 = 23 \][/tex]
[tex]\[ -120p = -600 \][/tex]
[tex]\[ p = 5 \][/tex]

Step 4: Substitute [tex]\(p = 5\)[/tex] back into the expression for [tex]\(q\)[/tex]:
[tex]\[ q = 18 \cdot 5 - 89 \][/tex]
[tex]\[ q = 90 - 89 \][/tex]
[tex]\[ q = 1 \][/tex]

So, the solutions for [tex]\(p\)[/tex] and [tex]\(q\)[/tex] are:
[tex]\[ p = 5, \quad q = 1 \][/tex]

### Equations for [tex]\(m\)[/tex] and [tex]\(n\)[/tex]:

Given equations:
1. [tex]\(5m - 2n = 20\)[/tex]
2. [tex]\(10m + 7n = 95\)[/tex]

We need to solve these equations simultaneously. Here's how:

Step 1: Solve the first equation for [tex]\(n\)[/tex]:
[tex]\[ 2n = 5m - 20 \][/tex]
[tex]\[ n = \frac{5m - 20}{2} \][/tex]

Step 2: Substitute this expression for [tex]\(n\)[/tex] into the second equation:
[tex]\[ 10m + 7\left(\frac{5m - 20}{2}\right) = 95 \][/tex]

Step 3: Simplify and solve for [tex]\(m\)[/tex]:
[tex]\[ 10m + \frac{35m - 140}{2} = 95 \][/tex]
[tex]\[ 10m + 17.5m - 70 = 95 \][/tex]
[tex]\[ 27.5m - 70 = 95 \][/tex]
[tex]\[ 27.5m = 165 \][/tex]
[tex]\[ m = 6 \][/tex]

Step 4: Substitute [tex]\(m = 6\)[/tex] back into the expression for [tex]\(n\)[/tex]:
[tex]\[ n = \frac{5 \cdot 6 - 20}{2} \][/tex]
[tex]\[ n = \frac{30 - 20}{2} \][/tex]
[tex]\[ n = \frac{10}{2} \][/tex]
[tex]\[ n = 5 \][/tex]

So, the solutions for [tex]\(m\)[/tex] and [tex]\(n\)[/tex] are:
[tex]\[ m = 6, \quad n = 5 \][/tex]

### Summary:
[tex]\[ \begin{array}{ll} 3 a + b = 13 & a = 3 \\ 6 a - 7 b = -10 & b = 4 \\ 6 p - 7 q = 23 & p = 5 \\ 18 p - q = 89 & q = 1 \\ 5 m - 2 n = 20 & m = 6 \\ 10 m + 7 n = 95 & n = 5 \\ \end{array} \][/tex]