Simple calculation: 30 × (4 / 5 + 5 / 6) =? 2 / 15 × 3 + 13 / 15 △ 1 / 3 =?

Simple calculation: 30 × (4 / 5 + 5 / 6) =? 2 / 15 × 3 + 13 / 15 △ 1 / 3 =?

30×(4/5+5/6)
=30×(4/5)+30×(5/6)
=6×4+5×5
=24+25
=49
(2/15)×3+(13/15)÷1/3
=(2/15)×3+(13/15)×3
=3×(2/15+13/15)
=3×1
=3

1 / 2 + 3 / 4-6 / 5 6 / 7-1 / 2 + 4 / 5 3 / 4 - (7 / 12-5 / 7) 2 / 3 + (13 / 15 + 1 / 3) 15 / 9-2 / 7-5 / 7
Solve the equation x + 5 / 6 = 5 / 2 x-3 / 4 = 2 / 3 9 / 7-x = 2 / 5

1/2+3/4-6/5
=10/20+15/20-24/20
=1/20
6/7-1/2+4/5
=5/14+4/5
=81/70
3/4-（7/12-5/7）
=3/4-7/12+5/7
=1/6+5/7
=37/42
2/3+（13/15+1/3）
=2/3+1/3+13/15
=1+13/15
=1 and 13 / 15
15/9-2/7-5/7
solve equations
x+5/6=5/2
x=5/2-5/6
x=5/3
x-3/4=2/3
x=2/3+3/4
x=17/12
9/7-x=2/5
x=9/7-2/5
x=31/35

Simple calculation of 9 / 13 - (3 / 13 + 12 / 26)

9/13-(3/13+12/26)
=9/13-(3/13+6/13)
=9/13-9/13
=0

2.9 * 0.45 + 0.29 * 4.2 + 0.029 * 13 simple calculation

2.9*0.45+0.29*4.2+0.029*13
=2.9*0.45+2.9*0.42+2.9*0.13
=2.9*（0.45+0.42+0.13）
=2.9*1
=2.9