Properties of equality have nothing to do with it. The associative and commutative properties of multiplication are used (along with the distributive property and the fact of arithmetic: 9 = 10 - 1).
All of these problems make use of the strategy, "look at what you have before you start work."
1. = (4·5)·(-3) = 20·(-3) = -60 . . . . if you know factors of 60, you can do this any way you like. It is convenient to ignore the sign until the final result.
2. = (2.25·4)·23 = 9·23 = 23·10 -23 = 230 -23 = 207 . . . . multiplication by 4 can clear the fraction in 2 1/4, so we choose to do that first. Multiplication by 9 can be done with a subtraction that is often easier than using ×9 facts.
4. = (2·5)·12·(-1) = 10·12·(-1) = (-1)·120 = -120 . . . . multiplying by 10 is about the easiest, so it is convenient to identify the factors of 10 and use them first. Again, it is convenient to ignore the sign until the end.
5. = 0 . . . . when a factor is zero, the product is zero
Answer:
Step-by-step explanation:
Given expression:
Remove parentheses:
Collect like terms:
Combine like terms:
Answer:
Total number of coins Nancy and bill have = 6x - 5
Step-by-step explanation:
Nancy and bill collect coins. Nancy has x coins. Bill has 5 coins fewer than five times the number of coins Nancy has. Write and simplify an expression for the total number of coins Nancy and bill have . Simplify your answer .
Let
Number of Nancy's coins = x
Number of Bill's coins = 5x - 5
Total number of coins Nancy and bill have = Number of Nancy's coins + Number of Bill's coins
= x + (5x - 5)
= x + 5x - 5
= 6x - 5
Total number of coins Nancy and bill have = 6x - 5
