Question 96438
average = (score1+score2+score3+score4)/4

We need average to be 70 or more:

70 <= (75+63+68+s)/4

70 <= (206+s)/4

Distribute:

70 <= 51.5 + s/4

Subtract 51.5:

18.5 <= s/4

Multiply by 4:

74 <= s

Check:

(75+63+68+74)/4 = 70