Need the left side to equal the right side

Use the elimination method to solve the system of equations -x+5y=-4 and 4x+3y=16

The area of a 25-inch tv screen is 300 square inches. the area of a 40-inch tv screen is 768 square inches. the are of the smaller screen is what percent of the area of the larger screen?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is