Answer:
x=30m
Explanation:
Smaller triangle of sizes 26m and 10m...
using Pythagoras rule...let the middle line that so the triangle be y...
26² = 10²+y²
26²-10²=y²
y²=676-100
y²=576
y=√576
y=24m
the middle line is now 24m
now the larger triangle of sizes 18m, 24m and x...
using Pythagoras rule...
x²=24²+18²
x²=576+324
x²=900
x=√900
x=30m