We know y = 4x - 3t. We are given the values of x and t and we need to work out the value of y. So we shall substitute the given values of x and t to work out y. y = 4 X 2 - 3 X 5, and so using the laws of BIDMAS which stands for Brackets Indices Division Multiplication Subtraction, we must do 4 X 2 and 3 X 5 first, so y = 8 - 15 as 4 X 2 = 8 and 3 X 5 = 15. Therefore y = -7 as 8 - 15 = -7.