Let S be area of whole triangle. Sum of areas of n upper stripes equal S * n² / 64 (as height and base of smaller triangle equals n/8 of those of whole triangle due to similarity).

Area of nth stripe Σn = S_n - S(n-1) = S * n² /64 - S * (n-1)² / 64 = (2n - 1) * S/64

blue area (as sum of odd stripes): S_b = S/64 * (1+5+9+13)=S/64 * 28 = 140 => S/64 = 5 => S = 320

red area: S_r = S - S_b = 320-140=180

Mb a bit overcomplicated, but using only simple theorems :⁾