In how many ways can you roll either a sum of 4 or a sum of 11 with a pair of dice?

(i don't understand the mathematical way)

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.