Which answer is correct? Btw the audio is just reading the question

Tomas is making trail mix using granola and walnuts. he can spend a total of $12 on the ingredients. he buys 3 pounds of granola that costs $2.00 per pound. the walnuts cost $6 per pound. he uses the equation to represent the total cost, where x represents the number of pounds of granola and y represents the number of pounds of walnuts. he solves the equation for y, the number of pounds of walnuts he can buy. answer- b tomas added 6 to both sides of the equation instead of subtracting 6. just took the test

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25

4. bob solved the inequality problem below incorrectly. explain his error and redo the problem showing the correct answer. −2x + 5 < 17 −2x + 5-5 < 17-5 -2x/-2 < 12/-2 x < -6