The correct answer would be A) 80 because if we organize all the tests scores from smallest numbers to biggest, and cross out numbers from each side, and keep going till one is left, we see 80 is the last number in the middle. *below is a image of my work.
equation 2 5N+10D=3000 This is for equation 1 N=500-d Substitute into equations 2 and solve for D 5N+10D=3000 5(500-D)+10D=3000 2500-5D+10D=3000 5D=500 D=100 Lets go back the equation 1 N=500-D N=500-100 N=400 there are 400 Nickles and 100 Dimes