What should be in each box

3/7 in box 3

2/7 in box 1

42 in box 2

The first box (y+4/7=6/7) should have 2/7

---Subtract 4/7 from both sides to get y alone. y=2/7

The second box (17+b=60) should have 43

---Subtract 17 from both sides to get b alone. b=43

The third box (6/7=m+3/7) should have 3/7

---Subtract 3/7 from both sides to get m alone. m=3/7