Type the correct answer in each box.
a=(1, -2, 3, 4) and b=(-5, 6, -7, 8) in c = 2a + 3b, the entry represented by C₂₄ is _. in d = 3a - 2b, the entry represented by d13 is _.

a. -5; 3
b. 15; -2
c. 25; 1
d. 13; 7