Известно что cos альфа равно 4/5 и 0

1)
1 1/12 + 3 3/4 + x = 4 1/2
1 1/12 + 3 9/12 + x = 4 1/2
4 10/12 + x = 4 1/2
x = 4 1/2 - 4 5/6
x = - (4 5/6 - 4 3/6)
x = - 2/6 
x = -1/3

2)
-( 5 2/3 - 1 3/5) - x = 6 1/3
-(5 10/15 - 1 9/15) - x = 6 1/3
-4 1/15 - x = 6 1/3
x = -(6 1/3 + 4 1/15)
x = -(6 5/15 + 4 1/15)
x = - 10 6/15
x = -10 2/5

3)
x - (7 10/18 - 5 3/18) = -3 1/2
x - 2 7/18 = -3 1/2
x = -(3 1/2 - 2 7/18)
x = -(3 9/18 - 2 7/18)
x = -1 2/18
x = -1 1/9

4)
x - (-4 3/5 + 3 4/7) = -8 1/14
x + 4 21/35 - 3 20/35 = -8 1/14
x + 1 1/35 = -8 1/14
x = -(8 1/14 + 1 1/35)
x = -(8 5/70 + 1 2/70)
x = -9 7/70
x = -9 1/10

Сколько снимков сделал игорь

3 5/8 + 1 2/3 = 29/8 + 5/3 = (29 × 3 + 5 × 8)/24 = 87/24 + 40/24 = 127/24 = 5 7/24
4 4/9 - 2 5/6 = 40/9 - 17/6 = (40 × 2 - 17 × 3)/18 = 80/18 - 51/18 = 29/18 = 1 11/18
6 712 + (5 340 - 4 815)= 7 43/84
1) 5 3/40 - 4 8/15 = 203/40 - 68/15 = (203 × 3 - 68 × 8)/120 = 609120 - 544/120 = 65/120 = 13/24
2) 6 7/12 + 13/14 = 79/12 + 13/14 = (79 × 7 + 13 × 6)/84 = 553/84 + 78/84 = 631/84 = 7 43/84

3х+х=360
4х=360
х=360:4
х=90
Во второй день автомобиль проехал 90 км
90*3=270
В первый день автомобиль проехал 270 км