3) (5х + 8) - (8х + 14) = 9
5х + 8 - 8х - 14 = 9
5х - 8х = 9 - 8 + 14
- 3х = 15
х = 15 : (-3)
х = - 5
- - - - - - - - - - - -
4) 2,7 + 3у = 9(у - 2,1)
2,7 + 3у = 9у - 18,9
2,7 + 18,9 = 9у - 3у
6у = 21,6
у = 21,6 : 6
у = 3,6
- - - - - - - - - - - -
5) 0,3(8 - 3у) = 3,2 - 0,8(у - 7)
2,4 - 0,9у = 3,2 - 0,8у + 5,6
- 0,9у + 0,8у = 3,2 + 5,6 - 2,4
- 0,1у = 6,4
у = 6,4 : (-0,1)
у = - 64
- - - - - - - - - - - -
6) 5/6(1/3х - 1/5) = 3х + 3 1/3
(5/18)х - 1/6 = 3х + 3 1/3
(5/18)х - 3х = 3 1/3 + 1/6
- (2 13/18)х = 3 2/6 + 1/6
- (49/18)х = 3 3/6
- (49/18)х = 3 1/2
- (49/18)х = 7/2
х = 7/2 : (-49/18)
х = 7/2 · (-18/49)
х = - (1·9)/(1·7)
х = - 9/7
х = - 1 целая 2/7
(-1.25+ 1_7/8) : (-1_1/16-0.5)= -0.4
1 3 2
1) -1.25+1_7/8 = -1_1/4+1_7/8 = -1_2/8+1_7/8 = 5/8
2) -1_1/16 - 0.5 = -1_1/16 - 1/2 = -1_1/16 - 1/2 = -1_1/16 - 8/16 = -1_9/16
3) 5/8 : (-1_9/16) = - 5/8 * 25/16 = (-5*16) / (8*25) = - 2/5 = -0.4