First, we convert all measurements to meters:
1 dm=0.1 m 1 cm=0.01 m So we have:
23.8 dm=23.8⋅0.1 m=2.38 m 970 cm=970⋅0.01 m=9.7 m 31 dm=31⋅0.1 m=3.1 m 96 dm=96⋅0.1 m=9.6 m Now, we substitute these values into the expression:
(74.3 m−2.38 m)⋅(9.7 m−3.1 m)+3.8 m⋅9.6 m =(71.92 m)⋅(6.6 m)+3.8 m⋅9.6 m =474.672 m2+36.48 m2 =511.152 m2