Hey!
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Let $0.68 per pound beans be (b)
Let $0.20 per pound beans be (p)
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~Total amount of pounds:
b + p = 120
~Total cost
b + p = 120 × 0.54
b + p = 64.8
~Expression
0.68b + 0.20p = 64.8
~Multiply 10 to both sides
0.68b * 10 + 0.20p * 10 = 64.8 * 10
~Simplify
6.8b + 2p = 648
~Divide 2 to both sides
6.8b/2 + 2p/2 = 648/2
~Simplify
3.4b + p = 324
~Subtract
3.4b + p = 324
- b + p = 120
~Simplify
2.4b = 204
~Divide 2.4 to both sides
2.4b/2.4 = 204/2.4
~Value of b
b = 85
~New expression
85 + p = 120
~Subtract 85 to both sides
85 + p - 85 = 120 - 85
~Value of p
p = 35
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My answer is reasonable because 85 + 35 equals 120 pounds.
~If we check
85 * 0.68 = 57.8
35 * 0.2 = 7
57.8 + 7 = 64.8
We get 64.8 which we can say it is correct because if we go back into our work we can see that we used the expression b + p = 64.8 which in this case by checking our work our answer is reasonable.
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Hope This Helped! Good Luck!