The sum of the digits of a two-digit number is 8. if the number is multiplied by 4, the result is 104. write and solve a system of equations. find the number. solve using substitution.

Let
xy> a two-digit number

we know that
xy=10x+y

x+y=8> x=8-y> equation 1
(10x+y)*4=104>divide by 4 both sides> 10x+y=26> equation 2

substitute equation 1 in equation 2
10*[8-y]+y=26> 80-10y+y=26> 9y=80-26> y=54/9---> y=6
x=8-y> x=8-6> x=2

the two-digit number is xy> 26

the answer is
26

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)