.efficiency-formula{width:211px; height:251px ;}
.efficiency-problem{width:66px; height:140px ;}
.efficiency-problem2{width:178px; height:131px ;}
.efficiency-formula2{width:162px; height:43px ;}
.efficiency-problem3{width:213px; height:109px ;}
.efficiency-problem4{width:180px; height:128px ;}
.efficiency-formula3{width:156px; height:43px ;}
.efficiency-formula4{width:225px; height:96px ;}