Answer:
- 4
- 25
Step-by-step explanation:
A calculator is your friend for such problems.
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Evaluating these by hand, the <em>Order of Operations</em> applies. First you do what's in parentheses, then you do multiplication, then addition/subtraction.
1. (3/4)·(12·4 -16) -20 = (3/4)(48 -16) -20 = (3/4)·32 -20 = 24 -20 = 4
2. (5/9)·(12·6 -42 +15) = (5/9)·(72 -42 +15) = (5/9)·(30 +15) = (5/9)·45 = 25
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Of course, the <em>Order of Operations</em> applies within each level of parentheses.
Adding the opposite of a number is the same as subtraction. Likewise, subtracting the opposite of a number is the same as adding the number. The usual associative and commutative properties of addition and multiplication apply. Among other things, that means you can compute the product of an integer and a fraction in any convenient way:
(3/4)·32 = 3·(32/4) = 3·8 = 24
(5/9)·45 = 5·(45/9) = 5·5 = 25
