How to find matrix for linear transformation?

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?