ANSWER:

Mass of copper in 1 peso coin : 4.125 gr

Further explanation

The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm), or mole fraction.

Percent mass of the component shows the total mass of the component in the overall mass of a compound / mixture

A 1 peso coin has a mass of 5.5 grams

1 peso coin containing 75% copper by mass

So the mass of copper:

\begin{gathered}\rm mass~of~copper=\dfrac{mass~of~copper}{mass~of~peso~coin}\\\\75\%=\dfrac{mass~of~copper}{5.5~gr}\\\\mass~of~copper=75\%\times 5.5\\\\mass~of~copper=\boxed{\bold{4.125~gr}}\end{gathered}

mass of copper=

mass of peso coin

mass of copper

75%=

5.5 gr

mass of copper

mass of copper=75%×5.5

mass of copper=

4.125 gr