51.2×4.6＋20×1又4分之1＋63.7×5.4
=51.2×4.6＋20×1又4分之1＋51.2×5.4 +12.5×5.4
=51.2×（4.6+5.4）+25+67.5
=51.2×10+92.5
=512+92.5
=604.5