N = Present Nancy ages
C = Present Cathy ages
Nancy is 3 times as old as Cathy mean:
N = 3 C
In seven years Nancy will be N + 7 yrs old , Cathy will be C + 7 yrs old
In seven years, she will be ten years older than Cathy Mean:
N + 7 = C + 7 + 10
N + 7 = C + 17 Subtract 7 to both sides
N + 7 - 7 = C + 17 - 7
N = C + 10
Replace N = 3 C in this equation
3 C = C + 10 Subtract C to both sides
3 C - C = C + 10 - C
2 C = 10 Divide both sides by 2
C = 5 yrs
N = 3 C = 3 * 5 = 15 yrs
Proof:
In seven years, Nancy will 15 + 7 = 22 yrs old
Cathy will be 5 + 7 = 12 yrs old
22 - 12 = 10 yrs
1.Nancy is 3 times as old as Cathy. In seven years, she will be ten years older than Cathy. What are their present age?
1 answer