Add columns. C1←C1+C2+C3+C4: each entry of column 1 becomes 10. So
Δ=101111234134124123.
Row operations. L2←L2−L1, L3←L3−L1, L4←L4−L1:
Δ=101000212−131−2−14−3−2−1.
Expand along column 1.
Δ=1012−11−2−1−3−2−1.
Compute the 3×3. L2←L2−2L1, L3←L3+L1:
=101001−40−34−4=10⋅1⋅(−4)⋅(−4)=160.
Conclusion. Δ=160.