19. (X+5)-3
20. 2a
21.3b
22. 5y-5
23. 1/2n-15
The results in the question conclude that it is an isosceles triangle so your answer can vary; for example, your could be 10, 22, 18 which would make the perimeter 50 like the question states. So your answer will vary anyways you just have to remember that it is an isosceles triangle so all three sides will be a different length.
-3^2= -(3)^2
The exponent of 2 only applies to the number 3. -(3)^2 should equal -9. This is true because according to the order of operations, exponents should be evaluated before multiplication. The negative sign here represents -1* 3^2.
If you want to find -3 to the power of 2 it must be written (-3)^2.
5 would be the digit in the tenths place
3/6 (r-7) =1 The answer is r=7
