63×3/8+61×5/8=63-63×5/8+61×5/8=63-5/8×(63-61)=63-5/8×2=63-5/4=61.75
63x3/8+61x5/8=2x3/8+61x3/8+61x5/8=3/4+61x(3/8+5/8)=3/4+61x1=61又3/4