`(x-32):16=48`
`x - 32 = 48 × 16`
`x - 32 = 768`
`x = 768 - 32`
`x = 736`
`814-(x-305) =712`
` 814-x+305 = 712`
`x=814+305-712`
`x=1119 - 712`
`x=407`
`x+(x+1)+(x+2)+⋯+(x+100)=10100`
` x+x+1+x+2+.... +x+100 = 10100`
`(x+x+...+x) + ( 1+2+...+100) = 10100`
`101x + 50.(1+100) = 10100`
`101x + 50.101 = 10100`
` 101.(x+50) = 10100`
` x + 50 = 10100 : 101`
` x+ 50 = 100`
` x = 100-50`
`x=50`
`xy-2x=5`
`x(y-2)=5`
`⇒` `x;(y-2)∈Ư(5)`
`⇒ x;(y-2) ∈ {(-1;-5);(-5;-1);(1;5);(5;1)}`
$\text{mà x là số tự nhiên}$
$\text{nên x∈{1;5}}$
`⇒y-2 ∈ {5;1}`
`⇒ y∈{7;3}`
$\text{Vậy cặp (x;y)∈{(1;7);(5;3)}}$
