So represent number as xy remember that since x is in the tens place, the value of the number is 10x+y x+y=7 if 9 is subtracted from (10x+y), then the answer will be the number with the digits reversed (10y+x) find the number
x+y=7 (10x+y)-9=(10y+x) 10x+y-9=10y+x subtract x from both sides 9x+y-9=10y subtract y from both sides 9x-9=9y add 9 to both sides 9x=9y+9 9(x)=9(y+1) divide both sides by 9 x=y+1 we also have x+y=7 isolate x by subtracting y from both sides x=7-y subsitute (7-y) for x in othe requation 7-y=y+1 add y to both sides 7=2y+1 subtract 1 from both sides 6=2y divide both sides by 2 3=y
subsitute x+y=7 x+3=7 subtract 3 from both sides x=4 number=10x+y 10(4)+3 40+3 43 the number is 43
x is multiplied by two because we are looking for twice of x. 11 is added to the 2x because we are looking for eleven more than the sum of twice of x. Since 2x + 11 is less than 44, we use the lesser than ( < ) symbol.
