a) Evaluate:
0.015×(0.042+0.030)2.4×(0.123−0.095)×0.009
Step 1: Simplify the expressions inside the parentheses.
0.123−0.095=0.028
0.042+0.030=0.072
Step 2: Substitute these values back into the expression.
0.015×0.0722.4×0.028×0.009
Step 3: Calculate the numerator.
2.4×0.028=0.0672
0.0672×0.009=0.0006048
Step 4: Calculate the denominator.
0.015×0.072=0.00108
Step 5: Divide the numerator by the denominator.
0.001080.0006048=0.56
The evaluated value is 0.56.
b) Simplify:
143+[5−243÷53]−[53−1of421]
Step 1: Convert all mixed numbers to improper fractions and simplify the first bracket in the third term.
143=41×4+3=47
243=42×4+3=411
421=24×2+1=29
53−1=52
The expression becomes:
47+[5−411÷53]−[52of29]
Step 2: Perform the division inside the first square bracket.
411÷53=411×35=1255
The expression becomes:
47+[5−1255]−[52of29]
Step 3: Perform the subtraction inside the first square bracket.
5−1255=125×12−1255=1260−1255=125
The expression becomes:
47+125−[52of29]
Step 4: Perform the "of" (multiplication) operation inside the second square bracket.
52of29=52×29=1018=59
The expression becomes:
47+125−59
Step 5: Find a common denominator for 4, 12, and 5, which is 60. Convert the fractions.
47=4×157×15=60105
125=12×55×5=6025
59=5×129×12=60108
The expression becomes:
60105+6025−60108
Step 6: Perform the addition and subtraction from left to right.
60105+25−108=60130−108=6022
Step 7: Simplify the fraction.
6022=3011
The simplified value is 3011.
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