Answer :

Let's solve the equation [tex]\(\frac{90 + 11b}{99} = 0.3(a + b)\)[/tex] step-by-step:

1. Equation Setup: We start with the given equation:
[tex]\[ \frac{90 + 11b}{99} = 0.3(a + b) \][/tex]

2. Clear the Fraction: To eliminate the fraction, multiply both sides of the equation by 99:
[tex]\[ 90 + 11b = 99 \times 0.3(a + b) \][/tex]

3. Simplify the Right Side: Calculate [tex]\(99 \times 0.3\)[/tex]:
[tex]\[ 99 \times 0.3 = 29.7 \][/tex]
Thus, the equation simplifies to:
[tex]\[ 90 + 11b = 29.7(a + b) \][/tex]

4. Distribute on the Right Side: Distribute [tex]\(29.7\)[/tex] across [tex]\(a + b\)[/tex]:
[tex]\[ 90 + 11b = 29.7a + 29.7b \][/tex]

5. Rearrange the Equation: Move all terms involving [tex]\(a\)[/tex] and [tex]\(b\)[/tex] to one side of the equation to isolate [tex]\(a\)[/tex]:
[tex]\[ 90 + 11b - 29.7b = 29.7a \][/tex]

6. Combine Like Terms: Combine the [tex]\(b\)[/tex] terms on the left side:
[tex]\[ 90 + (11b - 29.7b) = 29.7a \][/tex]
[tex]\[ 90 - 18.7b = 29.7a \][/tex]

7. Solve for [tex]\(a\)[/tex]: Isolate [tex]\(a\)[/tex] by dividing both sides by 29.7:
[tex]\[ a = \frac{90 - 18.7b}{29.7} \][/tex]

8. Express [tex]\(a\)[/tex] in Simplified Form: Simplify the fraction:
[tex]\[ a = 3.03030303030303 - 0.62962962962963b \][/tex]

So, the solution to the equation [tex]\(\frac{90 + 11b}{99} = 0.3(a + b)\)[/tex] is given by:
[tex]\[ a = 3.03030303030303 - 0.62962962962963b, \quad \text{for any value of } b. \][/tex]