I am trying to solve for x in the following equation:
Where I am trying to solve for x but the integral is too big to do by hand. This is my attempt in MatLab
clc
clear all
close all
syms x t
eqn = (1-(1/(1.3*10^12))*int((t*15)*exp(-t),0,16*x)) == 10^(-4)
sol = solve(eqn,x)
this is the result that I got 
. The correct number should be approximately 2.2. I am very thankful for your help.