The 10$ is added on because it's a one time exchange and the 8 is multiplied by the x because for every hour you add 8$ to the price and y is the total price at the end depending on x.
To find the area of a triangle uses the equation base*height/2. For this equation, we have 26 * h/2 = 195. This means that 26 * h = 195 * 2. 26 * 15 = 390, so your answer is 15 cm.
