Help is needed over here.

Solve                                           A  =  (1/2)(b₁ + b₂)h

Multiply both sides by 2:            2A  =  (b₁ + b₂)h

Divide both sides by b₁ + b₂:     2A/(b₁ + b₂)  =  h

 

Write                                      y = (-2/3)x - 7 in standard form

Multiply both sides by 3:      3y  =  -2x - 21

Add 2x to both sides:           2x + 3y  =  -21

 

Write in slope-intercept form:      5x + 2y  =  -6

Subtract 5x from both sides:               2y  =  -5x - 6

Divide both sides by 2:                          y  =  (-5/2)x - 3