How to solve interior angles of a triangle

What is the y-intercept of the graph of the equation y=3(2^x)

Jenisey has $24 to spend on seven pencils. after buying them she had $10. how much did each pencil cost.?

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters