The interest is computed from
... I = Prt
where P is the principal amount ($569), r is the rate (0.045) and t is the time in years (250/360).
... I = $569×0.045×250/360 ≈ $17.78
Please note that time is not rounded. Rather, the exact value (25/36) is used in the calculation. The only rounding of any number is done at the end, where the amount is rounded to the nearest cent. (Your text authors should know this.)
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If you follow the problem instructions (which Valerie's lender will <em>not</em> do), the interest is calculated as ...
... t = 250/360 = 0.6944444... ≈ 0.69 . . . . years
... I = $569×0.045×0.69 ≈ $17.67
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Note the rounding of intermediate numbers (time) introduces an error of about $0.11 in the answer.
The least common multiple of each is 2. 2 x 25= 50. 2 x 30= 60 and 2 x 36=72
Just combine the two expression:
(3x-2)+(2x-1)
= 3x-2+2x-1
=5x-3
A is your answer