Solve a system of equations using substitution

Question

Andrew and his little sister are saving up money to buy a joint birthday present for their mother. Andrew already has $27 saved and plans to save $14 per week from his allowance. His sister has $21 saved so far and will save $17 per week from hers. The two siblings will soon have saved the same amount towards their mother's gift. How much will each one have saved? How long will that take?

Answer 1

14w + 27 = 17w + 21

3w = 6

w = 2

 

14(2) + 27 = 28 + 27 = 55

 

They will each have $55 in 2 weeks.