Explanation:
Ariana and Mackenzie exercised for 20 minutes more than Brinley and Seth.
x = Seth exercise minutes
Ariana minutes = 3x
Brinley minutes = 3x - 17
Mackenzie minutes = 1/2 × (3x - 17)
so, in total we have
3x + ½(3x - 17) = x + (3x - 17) + 20
statement 1 is true.
6x + (3x - 17) = 2x + 2(3x - 17) + 40
6x + 3x - 17 = 2x + 6x - 34 + 40
9x - 17 = 8x + 6
x = 23
statement 2 is false.
Brinley and Seth exercised together for
x + 3x - 17 = 23 + 3×23 - 17 = 4×23 - 17 = 75 minutes
statement 3 is false.
Mackenzie exercised for
½(3x - 17) = ½(3×23 - 17) = ½(69 - 17) = ½×52 = 26 minutes
statement 4 is true.