First you want to put them in equations. Say the first number is x and the second is y. So we know that x + y = 21 so that will be our first equation then we also know that y is 6 times bigger than x so we get 6x = y. Those are our two equations. Now we see that in the second equation y is already isolated and is equal to 6x so we will replace y in the first equation with 6x. Then we get x + 6x = 21 that can be simplified to 7x = 21 next to find the value of x we will isolate it by dividing each side by 7 then we get x= 3. So then we replace it into one of our equations to find the value of y. For example I will place it in the 6x=y equation and we get 6(3)= y. That goes to 18=y so our two numbers are 3 and 18 which check out and make 21
