1.
a):
`638 + 780 × 5 − 369 : 9`
`= 638 + 3900 − 369/9`
`= 4538 − 369/9`
`= 4538 − 41`
`= 4497`
b):
`(5/2 - 1/3) × 9/2 - 6/7`
`= (15/6 - 2/6) × (9/2) - 6/7`
`=` ${ \dfrac{15 - 2}{6}}$ `× (9/2) - 6/7`
`= 13/6 × (9/2) - 6/7`
`=` ${ \dfrac{13 × 9}{6 × 2}}$ `- 6/7`
`= 117/12 - 6/7`
`= 39/4 - 6/7`
`= 273/28 - 24/28`
`= 249/28`
c):
`895,72 + 402,68 − 634.87`
`= 1298,4 − 634,87`
`= 663,53`
d):
`100% + 28,4% − 36,7%`
`= 128,4% - 36,7%`
`= 0,917% = 91,7`
2.
a):
`435 − (x + 16) = 425 : 17`
`= 435 − x − 16 = 425/17`
`= 419 − x = 425/17`
`= 419 − x = 25`
`= − x = 25 − 419`
`= − x = − 394`
`x = 394`
b):
`(x + 4/3) × 7/4 = 5 - 7/6`
`= x × (7/4) + 4/3 × (7/4) = 5 - 7/6`
`= x × (7/4) +` ${ \dfrac{4 × 7}{3 × 4}}$ `= 5 - 7/6`
`= x × (7/4) + 7/3 = 5 - 7/6`
`= x × (7/4) + 7/3 = 30/6 - 7/6`
`= x × (7/4) + 7/3 =` ${ \dfrac{30 - 7}{6}}$
`= x × (7/4) + 7/3 = 23/6`
`= x × (7/4) = 23/6 - 7/3`
`= x × (7/4) = 23/6 - 14/6`
`= x × (7/4) =` ${ \dfrac{23 - 14}{6}}$
`= x × (7/4) = 9/6`
`= x × (7/4) = 3/2`
`= x × 3/2 = (4/7)`
`x =` ${ \dfrac{3 × 4}{2 × 7}}$
`x = 12/14`
`x = 6/7`
Cho mình xin hay nhất nha bạn!!!!
@Drew Mclntyre
