Question

Marcos ahorro $3270 en monedas de $10,$5 y $2.Si el numero de monedas de $10 excede en 20 a las de $5 y en 15 a las de $2.

Answer 1

Answer:

The number of $5 coins is 180

Step-by-step explanation:

Let

x ---> the number of $10 coins

y ---> the number of $5 coins

z ---> the number of $2 coins

we know that

$10x+5y+2z=3,270$ -----> equation A

$x=y+20$ ----> $y=x-20$ ----> equation B

$x=z+15$ ----> $z=x-15$ ----> equation C

Solve the system by substitution

Substitute equation B and equation C in equation A

$10x+5(x-20)+2(x-15)=3,270$

solve for x

$10x+5x-100+2x-30=3,270$

$17x-130=3,270$

$17x=3,270+130$

$17x=3,400$

$x=200$

Find the value of y

$y=x-20$

$y=200-20=180$

therefore

The number of $5 coins is 180