#include <bits/stdc++.h>

using namespace std;

// typedef long long i64;

int exgcd(int a, int b, int &x, int &y) {
    if (!b) {
        x = 1, y = 0;
        return a;
    } else {
        int c = exgcd(b, a % b, y, x);
        y -= a / b * x;
        return c;
    }
}

int main() {
    int T;
    for (scanf("%d", &T); T --; ) {
        int X, Y, P, Q, A, B, a, b, c, x, y;
        scanf("%d%d%d%d", &X, &Y, &P, &Q);
        A = P + Q;
        B = X + Y + X + Y;
        // printf("  A=%d,B=%d\n", A, B);
        c = exgcd(A, B, x, y);
        // printf("  c=%d,x=%d,y=%d   c=A*x+B*y\n", c, x, y);
        a = A / c;
        b = B / c;
        // printf("  a=%d,b=%d\n", a, b);
        y = -y;
        if (x < 0 || y < 0) x += b, y += a;
        // printf("  x=%d,y=%d\n", x, y);
        // assert(1ll * x * A - 1ll * y * B == c);
        // assert(x >= 0 && y >= 0);
        // assert(x <= b && y <= a);
        int dl = X - P - Q + 1;
        int dr = X + Y - P - 1;
        // printf("  dl=%d, dr=%d\n", dl, dr);
        if (dl >= 0) dl = (dl + c - 1) / c;
        else dl = dl / c;
        if (dr >= 0) dr = dr / c;
        else dr = (dr - c + 1) / c;
        // printf("  dl=%d, dr=%d\n", dl, dr);
        long long ans = LONG_LONG_MAX;
        for (int d = dl; d <= dr; d ++) {
            // assert(d * c > X - P - Q);
            // assert(d * c < X + Y - P);
            int k = d * x % b;
            if (k < 0) k += b;
            int m = d * y % a;
            if (m < 0) m += a;
            // printf("    d=%d, k=%d, m=%d\n", d, k, m);
            // assert(1ll * k * A - 1ll * m * B == d * c);
            long long t = 1ll * k * A;
            if (X - P <= c * d) t = t + P;
            else t = t + c * d - X;
            ans = min(ans, t);
        }
        if (ans == LONG_LONG_MAX) ans = -1;
        printf("%lld\n", ans);
    }
    return 0;
}