Complete the equation of the line whose slope is -2 and y intercept is(0,3)

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

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Need this at the city museum, child admission is 6 and adult admission is 9.20. on tuesday, 132 tickets were sold for a total sales of 961.60. how many adult tickets were sold that day?