What is 3x = 21? Please solve with work.

Hi!

To solve this equation, we need to isolate the x. To do this, we will use inverse operations.

The inverse operation for multiplication is division (3 is being multiplied by x,) so we will divide 3 on both sides:

3x/3 = x

21/3 = 7

Our equation now looks like this:

x = 7

You have nothing left to simplify, so you're done!

Hope this helps!

15/10, 30/20, 60/40, 120/80, 240/160, 480/320

Step-by-step explanation:

The number of push-ups is 2/3 the amount of sit-ups, so the ratio of sit-ups to push-ups is 3:2.

The easy way to do this is to double both 15 and 10 so your answer will stay an equivalent ratio. You will always have a 3:2 ratio this way.