Estimate if the fractions are closest to 0, 1/2, or 1, then add or subtract: 2/5 + 4/5
1 1/5 = 1
3/8 + 7/8
10/8 = 1 2/8 = 1 1/4
5/6 - 3/9
9/18 = 1/2
Press F11 Select menu option View > Enter Fullscreen for full-screen mode