Question

The ratio of the number of dolls Jacky had to the number of dolls Peter had was 5 : 2 but, after Jacky gave 15 dolls to Peter, they have an equal number of dolls. How many dolls did they have altogether?

Answer 1

Answer:

35 [$]

Step-by-step explanation:

1) if Peter's sum is p and Jacky's is j, then the ratio 5:2 in the condition can be written j/p=5/2;

2) the phrase 'after Jacky gave 15 dolls to Peter, they have an equal number of dolls' can be written as j-15=p;

3) using the two above it is possible to make up the system of two equations:

$\left \{ {{\frac{j}{p} =5/2} \atop {j-15=p}} \right. \ = > \ \left \{ {{j=2.5p} \atop {j-15=p}} \right. \ = > \ \left \{ {{j=25} \atop {p=10}} \right.$

4) finally, the have together 10+25=35 doll-s.