Answer:
8 ejercicios
Step-by-step explanation:
De acuerdo a la información dada, puedes plantear las siguientes ecuaciones:
x+y= 45 (1)
7x-1y= 19 (2)
x= ejercicios que resolvió bien
y= ejercicios que resolvió mal
Primero, puedes despejar x en (1):
x= 45-y (3)
Segundo, debes reemplazar (3) en (2):
7(45-y)-1y=19
315-7y-1y= 19
315-8y= 19
315-19= 8y
296= 8y
y= 296/8
y= 37
Tercero, debes reemplazar el valor de y en (3) para encontrar x:
x= 45-37
x= 8
De acuerdo a esto, la respuesta es que el hijo ha resuelto bien 8 ejercicios.
1. c (multiply by 3 to get 9x - 3y = 15)
2. c (add the new top expression with the bottom one to get 11x = 0) substitute 0 into either equation to get -5)
hope this helps!
Answer:
Step-by-step explanation:
the balloon starts at a height of 0 ft and rises at a rate of 100 ft.
Answer: first option 392.699 square feet.
Explanation:
1) The shape of the sidewalk is an ring with exterior radius equal to the radious of the fountain + 5 feet and inner radius equal to the radius of the fountain.
2) The area of such ring is equal to the area of the outer circle less the area of the inner circle (the fountain)
Area of a circle = π × r²
Area of the outer circle: π (10ft + 5 ft)² = π (15 ft)² = 225 π ft²
Area of the inner circle = π (10ft)² = 100 π ft²
Area of the ring (sidewald) = 225π ft² - 100π ft² = 125π ft² = 392.699 ft²
