So for this we will be using a system of equations, with one equation representing Shakira's sales and the other representing Jeff's sales. Our equations are such (Let x = oranges and y = grapefruit)
For this, I will be using the elimination method. So firstly, multiply both sides of the second equation by -4:
Next, add 5x+8y=235 and -12x-8y=-340 to get -7x = -105 . From here we can solve for x.
For this, just divide both sides by -7, and your answer is going to be x = 15.
Now that we know what x is, just substitute x for 15 in either equation to solve for y. For this I will be using the second equation.
Since we know that oranges cost $15 and grapefruit cost $20, just add them together to get your answer, which is $35.