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
Tom is spending more on tax totaling 23.54
while his cousin is only spending 18.72
How to get tax with percent take base price ex:22+ 7%
transform percent into a decimal : .07
now multiply the decimal times base price : 22x0.07
tax is a $1.54 now add that to your base price 22
and you get your total $23.54
