What is the answer to 3x-9=21

x=10

Step-by-step explanation:

Any number next to x like 3x you multiply so you take numbers 1-9 and put it as X  and work through every number and see which number makes the equation true.

3x-9=21

Move -9 to the other side. Sign changes from -9 to +9

3x-9+9=21+9

3x=30

divide by 3 for both sides

3x/3=30/3

Cross out 3 and 3, divide by 3 and then becomes 1*1*x=x

x=10

x=10

step-by-step explanation:

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.