Answer :
bruce=x
sarah=y
4x+2y=84
x=3y
subsitute
4(3y)+2y=84
12y+2y=84
14y=84
divide both sides by 14
y=6
sarah=6
x=3(y)
x=3(6)
x=18
bruce=18
sarah=6
sarah=y
4x+2y=84
x=3y
subsitute
4(3y)+2y=84
12y+2y=84
14y=84
divide both sides by 14
y=6
sarah=6
x=3(y)
x=3(6)
x=18
bruce=18
sarah=6