Seven times a 2 negative digit number is equal to 4 times the number obtained by reversing the digits. The difference between the digits is 1. Find the number.

Question

Word problem that needs to be solved by using simultaneous equations.

Answer 1

7(-ab)=4(-ba)

7(-10a-b)=4(-10b-a)

-70a-7b=-40b-4a

-66a+33b=0

a-b=1 --------> a=b+1

substitute

-66(b+1)+33b=0

-66b-66+33b=0

-33b-66=0

-33b=66

b=-2

a=-2+1

a=-1

-12 is the number

7(-12)=4(-21)

-84=-84