An equation is an mathematical expression where two things are equal. In this case we have a number and an product. The problem states that 20 is 4 times as many as 5. The "is" word gives us a hint that there is the equal sign, and the "times" gives us a hint that it is a product. So we can express this with:
To find the area of a parallelogram you multiply the base times the height, or the length times the height. This is why you multiply 5x8 to get 40. The substitution could be 5 x 8 = X
