How do I solve this?

Question

How do I solve this? Briana and her sister Molly both want to buy the same model bike. Briana needs $73 more before she can afford it. Molly needs $63 more. If they combine their money they will have just enough for the bike. How much does it cost?

Answer 1

If x = cost of bike, then...

x-73 = B (Birana's money)

x-63 = M (Molly's money)

B + M = x (cost of bike)

B + M = x = x-73 + x-63

2x-x = 136

x = 136 

Bike cost $136

Briana has $63 and Molly has $73