18.
-2(-9)+3
18+3
21
Explanation: -2(-9) When multiplying numbers that have both a negative sign, the answer is positive. Multiply normally.
19.
-6(-4)0
24(0)
0
Explanation: -6(-4) As I explained before, the answer would be positive.
24(0) Every number multiplied by 0 is 0.
20.
56+(-7)
49
Explanation: 56+(-7) Any problem like this is just basically going to be 56-7.
21.
-36+(-4)
-40
Explanation: -36+(-4) You are simply adding normally then adding the sign. This will only work if the signs are the same. (Signs are positive and negative.)
If the two triangles are similar you can use a proportion to solve for the length of the legs.

=

Now, you would cross multiply to get
4x=18
Now, you simplify that using the division property of equality.
You end up with
x=4.5
Therefore, the legs of the triangle with a base of 9 inches will each be 4.5 units long.
Answer:
Should be 5, hopes this helps
Step-by-step explanation:
That's it.