Robert bought some gifts that were each worth $25.90 at a store. He also bought one treat for himself that cost $4.00. If Robert bought three gifts, which equation shows how to calculate the total amount of money he spent at the store?
A.3 x 25.90 +4= 89.70
B. O 3 x 25.90 +4= 81.70
C.3 x (25.90 + 4) = 89. 70
D. O3 (25.90 + 4) = 81. 70

Find the solution of this system of equation -7x+y=-20 9x-3y=36

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)

Solve each quadratic equation by factoring and using the zero product property. 14x - 49 = x^2