Question

Uma mãe sempre reserva R$396,00 para dar de mesada para seus dois filhos. As quantias destinadas a cada um são proporcionais as suas idades, que são 12 e 21 anos. Quanto cada um recebe de mesada?

Answer 1

The oldest child receive Rs 252 and the youngest child receive Rs 144

Explanation:

The question in English is

A mother always reserves Rs 396.00 to give allowance for her two children. The amounts intended for each are proportional to their ages, which are 12 and 21 years. How much does each person receive from allowance?

Let

x ----> amount received by the oldest child

y ----> amount received by the youngest child

we know that

`x+y=396` ------> equation A

`(x)/(y)=(21)/(12)`

`x=(21)/(12)y` ------> equation B

Solve the system by substitution

Substitute the equation B in equation A and solve for y

`(21)/(12)y+y=396`

`(33)/(12)y=396`

`y=396*12/33`

`y=144`

Find the value of x

`x=(21)/(12)(144)=252`

therefore

The oldest child receive Rs 252 and the youngest child receive Rs 144