In the question you are to find positive b not negative b so you have to take negative b to the left hand side of the equation to become positive b and take 2aH to the right hand side to become -2aH
$250 = $75 + ? 45 × 3 = 135 135 + 75 = 210 210 + 45 = 255 ? = 180 $75 + ( 45 × 4 ) = 255 so she could save up 4 weeks worth of money plus the other 75 with an extra $5 to spend or save for something
