Answer
a). $2.3\times10^{-1}$
b). $7\times10^{15}$
c). $1.2\times10^{2}$
d).$-1.84\times10^{-1}$
Work Step by Step
a). $0.12+1.1\times10^{-1}=0.12+0.11=0.23=2.3\times10^{-1}$
b). $14.0\times10^{15}-700\times10^{13}=(1400-700)\times10^{13}=7\times10^{15}$
c). $-20+1.4\times10^{2}=-20+140=120=1.2\times10^{2}$
d).$-1.70\times10^{-1}-1.40\times10^{-2}=-0.17-0.014=-0.184=-1.84\times10^{-1}$