Question

Mary is 3 years older than Sarah.winifred is twice as old as Mary. Altogether thei ages total 89. How old is Sarah

Answer 1

sarah is 20 years old

Explanation:

We will represent Mary as m, Sarah as s and wilfred as W

so m= s+3, w= 2m

and s + w + m = 89

substitute m for s+3

so

w=2s + 6 and

2s+3+w=89

substitute w for 2s+6

2s + 3 +2s+6=89

4s+9=89

4s= 80

s=20