UEC Exam ratio problem

Question

I am going to sit for UEC exam and I am 15 years old and I need helps.

The question is as follow:

If p:q:r=3:5:7 and p+q=56
Find the value of p+q+r

Thank you

Answer 1

Using ratios, $\frac{3q}{5}=p$ so replace $p$ by its expression in terms of $q$:

$\frac{3q}{5}+q=56$ which gives $q=35$ and so $p=21$ and using the ratios given, $r=49$.

So $p+q+r=21+35+49=105$

Answer 2

Hint: From our starting equation we get $$p:q=3:5$$ so $$p=\frac{3}{5}q$$ and $$q+\frac{3}{5}q=56$$ Can you finish?