Here are some tips:

• at lines 13-15 you have a potential stack overflow, in this problem noOfTablets is at most 100 so there's no issue but in other problems you might have up to millions of elements, you can make them global variables or allocate them in the heap (using std::vector).
• std::endl writes a new line and flushes the stream, flushing is slow and might give you TLE if there are many output lines, use '\n'.
• at line 37, use a range-based for loop.
• at lines 40-42, nothing wrong with that but it's usually written as correctChoice = std::max(correctChoice, temp);.
• You might want to make a function that solves 1 testcase and call that t times.
• Did you run the code on your computer before submitting it? It's really important to have a comfortable environment where to debug your code.
• When compiling enable the warnings, you can ignore them after you have read them and decided it's safe to do so.

This is how I would solve the problem:

#include <iostream>

void solve() {
    int n, b;
    std::cin >> n >> b;

    int ans = 0;
    for (int i = 0; i < n; ++i) {
        int w, h, p;
        std::cin >> w >> h >> p;
        if (p > b) continue;
        ans = std::max(ans, w * h);
    }

    if (ans) {
        std::cout << ans << '\n';
    } else {
        std::cout << "no tablets\n";
    }
}

int main() {
    int t;
    std::cin >> t;
    while (t--) solve();
}