Question 1160612
<br>
Let x = grams of quinoa
Let y = grams of corn<br>
Then 0.145x = grams of protein in the quinoa
and 0.025y = grams of protein in the corn<br>
{{{x+y = 60}}}  the sample is 60 grams
{{{0.145x+0.025y = 4}}}  the amount of protein is 4 grams<br>
Usually when a system of linear equations has both equations in the form ax+by=c, I would use elimination.  But with the ugly coefficients in the second equation, I choose to use substitution.<br>
{{{y = 60-x}}}
{{{0.145x+0.025(60-x) = 4}}}<br>
I'll let you finish from there.<br>
Note that the last equation I show in my work is what would be my starting equation, if the instructions had not said to use a system of equations.  Nearly always, solving a problem using a single variable and a single equation is easier and faster than solving a pair of equations in two variables.<br>