If x:y = 7:4 and x+y = 88 , work out the value of x–y.

We know that x:y is 7:4, and therefore x is seven-elevenths of the total value of x and y. Therefore we can express x = 7/11 (x+y). Since we also know that the total of x+y is 88, we can substitute this into our x value. This means that x= 7/11 (88).Since 1/11 of 88 is 8, 7/11 is 8x7=56. Now that we have worked out the value of x, we can work out the value of y using the second equation in the question. If x is 56, that means that 56+y = 88, so y = 88-56 = 32.Now that we have both the values of x and y, we can perform the requested sum, x-y. x-y = 56-32 = 24.