दो व्यक्तियों की वर्तमान आयु क्रमश : 36 और 50 वर्ष है । यदि n साल बाद आयु का अनुपात 3 : 4 हो जाता है, तो n का मान ज्ञात करें ? 

Read the passage carefully and choose the best answer to each question out of the four alternatives.
The National Highways Network of India measures over 70,934 km as of 2010, including over 1,000 km of limited-access expressways. Out of 71,000 km of National Highways 15,000 plus km are 4 or 6 lanes and remaining 50,000 km are 2 lanes. The National Highways Authority of India (NHAI) is the nodal agency responsible for building upgrading and maintaining most of the national highways network. The national Highways Development Project (NHDP) is a major effort to expand and upgrade the network of highways. NHAI often uses a public-private partnership model for highway development, maintenance and toll collection. National highways constituted about 2% of all the roads in India, but carried about 40% of the total road traffic as of 2010. The majority of existing national highways are two-lane roads (one lane in each direction), though much of this is being expanded to four-lanes, and some to six or eight lanes. Some sections of the network are toll roads. Over 30,000 km of new highways are planned or under construction as par of the NHDP as of 2011. This includes over 2,600 km of expressways currently under construction. 

What is the responsibility of the NHAI? 

यदि (a + b):(b + c):(c + a) = 7:6:5 और a + b + c = 27, तो 1/a: 1/b :1/c का मान क्या होगा?