Can someone help me to answer this, please, and explain it. Please answer these 2 questions, I don't have more money to buy more questions. These 2 questions are different.

1.a.

1.b.

When 18.3 is added to 72.77, the result should be reported with digit(s) after the decimal point. When 49.04 is subtracted from 51.9, the result should be reported with digit(s) after the decimal point. When 18.3 is multiplied by 72.77, the answer should be reported to significant digit(s). When 51.9 is divided by 49.04, the answer should be reported to significant digit(s). A sample is found to contain 4.27107g of salt. Express this quantity in nanograms. ng