(4/15-1/5)*25 (7/12+5/36):13

(4/15 - 1/5 ) * 25 = (4/15 - 3/15 )*25 = 1/15 * 25 = 1/3 *5 = 5/3 = 1  2/3
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(7/12+5/36)/13 = (21/36 + 5/36) = 26/36 * 1/13 = 2/36 = 1/18