Có 3 người làm xét nghiệm virus . Gọi A ,B, C lần lượt là kết quả người thứ nhất, thứ hai, thứ ba dương tính a) kết quả người thứ hai âm tính
b) ít nhất có một kết quả xét nghiệm dương tính

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

answer: get a conversion sheet out i dont know the exact measurments

step-by-step explanation: divide the number of feet with the nu,ber of milrs and there your answer

the height of the surface increases from the center out to the sides of the road.

step-by-step explanation:

as we move out we move away from the x-axis.

and as mentioned in the problem statement that height of a road increases when we move away from the center x.

hence proved that 3rd option

the height of the surface increases from the center out to the sides of the road.

is the correct option.