Em uma loja de materiais de construção há azulejos quadrados de lado y cm vendidos a R$ 40,00 por m². Há um outro modelo de azulejo, também quadrado, cujo lado é 5 cm maior que o outro e custa R$ 80,00 por m². Nessas condições, a razão entre o preço de uma unidade do azulejo maior e o preço de uma unidade do azulejo menor, em função de y, é: Dado: 1 m² = 10 000 cm².

None of those are technically correct. 9.7 x 104 is actually 1,008.8, but if that answer was a choice, it would be that one. if you meant 9.7 times maybe a thousand or more or divided by 10 or more, than the answer choices would be correct, but other than that, they actually arent.

Ok here we go ..there are plenty of ways to solve such math problems but we will go for the smartest and easiest ..5x+2y=7  -2x+6y=9we rearrange them into the following ..by multiplying the 1st equation by 2 it becomes 10x + 4y = 14we rearrange it and so it becomes 10x = 14 - 4yas for the second equation we multiply it by 5 and rearrange it so it becomes as to the following ..-10x + 30y = 45rearranging so 10x = 30y -45now 10x equals both 14 - 4y and 30y -45so   14 - 4y = 30y -4531 = 26yy= 31/26 = 1.19 or around 1.2so by now we can calculate x easily as  -2x+6y=9so 2x = 6y -9 = 6 * 31/26 - 9 = -1.84  then x = - 0.92 or around -0.9best luck!