Express the fractions 1/2, 3/16, and 7/8 with an lcd

You first need to find the LCD (lowest common denominator). You will need to find the smallest number that is a multiple of all numbers that is the denominator (2, 16, 8). Or, to say it another way, all the numbers in the denominator need to be a factor of this number. 

You can find this by first checking if the largest number that is the denominator-- in this case 16-- is already the LCD, which means 16 is divisible by all the other numbers. 

If this does not work, then multiply all the numbers together to get the LCD-- since you multiplied them together, you know that they will all be factors of the product. 

However, you will be able to see that 16 is indeed the lowest common denominator: 

2 × 8=16 

8 × 2=16 

16 × 1=16 

So, after you find the LCD, multiply both the numerator and the denominator by the number that you would need to multiply the denominator to get the LCD (the whole point is that you want to get the denominator to be the LCD, but to do that you need to multiply both the top and bottom by the same number to keep the fraction the same). 

(1/2) x (8/8)= 8/16 

(3/16) x (1/1)= 3/16 

(7/8) x (2/2)= 14/16