Question 897206
y = number of quarters


If x = number of dimes, and if we have 50 coins (either quarters or dimes), then


x+y = 50


solve for y to get x = <font color="red">50 - y</font> (notice how I subtracted y from both sides to isolate x)


So there are <font color="red">50 - y</font> dimes if there are y quarters.