一、口算。
$7m×5=$
$103-34=$
$0.08×4=$
$868÷2=$
$x×27=$
$207+402=$
$0.56×2=$
$4.8÷8=$
$264-136=$
$0.72÷10=$
$3×a×b=$
$0.05×80=$
$1.6×20=$
$4.34-3.33=$
$1.77+3.11=$
$38.4÷6=$
$37×50=$
$770÷11=$
$1.27+3.16=$
$750÷30=$
$11.2+1.97=$
$135×6=$
$1.05×6=$
$12.35÷5=$
$4.2×10×b=$
$1-0.92=$
$9.8-1.2×t=$
$0.98÷14=$
$145×40=$
$0.05x×100=$

$7m×5=35m$
$103-34=69$
$0.08×4=0.32$
$868÷2=434$
$x×27=27x$
$207+402=609$
$0.56×2=1.12$
$4.8÷8=0.6$
$264-136=128$
$0.72÷10=0.072$
$3×a×b=3ab$
$0.05×80=4$
$1.6×20=32$
$4.34-3.33=1.01$
$1.77+3.11=4.88$
$38.4÷6=6.4$
$37×50=1850$
$770÷11=70$
$1.27+3.16=4.43$
$750÷30=25$
$11.2+1.97=13.17$
$135×6=810$
$1.05×6=6.3$
$12.35÷5=2.47$
$4.2×10×b=42b$
$1-0.92=0.08$
$9.8-1.2×t=9.8-1.2t$
$0.98÷14=0.07$
$145×40=5800$
$0.05x×100=5x$

二、根据等式的基本性质，在$◯$里填运算符号，在$□$里填数。
1. $x + 18 = 39$ $x + 18 - 18 = 39◯□$
2. $x - 75 = 24$ $x - 75 + 75 = 24◯□$
3. $6x = 72$ $6x ÷ 6 = 72◯□$
4. $x ÷ 3 = 45$ $x ÷ 3 × 3 = 45◯□$
5. $7x = b$ $7x ÷ 7 = b◯□$
6. $y ÷ 2 = a$ $y ÷ 2 × 2 = a◯□$

1. $x + 18 - 18 = 39-18$
2. $x - 75 + 75 = 24+75$
3. $6x ÷ 6 = 72÷6$
4. $x ÷ 3 × 3 = 45×3$
5. $7x ÷ 7 = b÷7$
6. $y ÷ 2 × 2 = a×2$